A manual resuscitator/ventilator is a hand-held device used to provide positive pressure ventilation to patients who are not breathing or are not breathing adequately or normally by manually compressing a bag connected to an airway tube, face mask or other airway adjunct. One common form of a manual resuscitator is a bag valve mask (BVM) that is also sometimes referred to as an ambu bag. In a BVM, the airway tube is connected to a mask that is designed to fit over the face of a patient. In another type of manual resuscitator, the airway tube is connected to an endotracheal tube or advanced airway device that is used to intubate/ventilate the patient. Use of manual resuscitators to ventilate a patient is usually called “bagging” the patient and is necessary in medical emergencies when the patient's breathing is insufficient (respiratory failure) or has ceased completely (respiratory arrest). Use of the manual resuscitators force-feeds air or oxygen into the lungs in order to inflate them under pressure thus constituting a means to manually provide ventilation to a patient.
When using a manual resuscitator such as a BVM, bag compressions/ventilations performed improperly, such as at improper rates and/or durations, have been shown to cause detrimental effects including low survival rates in patients in cardiac arrest and life threatening complications such as gastric regurgitation and aspiration that can later lead to death. It is widely known from many clinical studies that very often ventilation rates are administered far in excess of the recommended and safe amounts established. This is very often done even by highly experienced well trained EMS personnel and personnel and can cause detrimental effects where life threatening conditions already exist in patients. Studies have found that even among highly trained and experienced medical personnel, the quality of manual and BVM ventilation is inconsistent and does not meet published guidelines. In one clinical observation study, it was found that ventilation rates during the field application of CPR (cardiopulmonary resuscitation) in a city with well-trained EMS personnel were observed to be far in excess of those recommended by the American Heart Association. This study found that professional rescuers responder and medical personnel consistently and inadvertently hyper-ventilated patients during actual resuscitations. This hyperventilation can lead to detrimental hemodynamic and survival consequences during low flow states such as when CPR is applied. The study concluded that unrecognized and inadvertent hyper-ventilation may be contributing to the currently dismal survival rates from cardiac arrest.
Manual resuscitators often are manufactured in different sizes to be used on patients of different age categories and are commonly available in adult, child, infant and neonate sizes. Particularly in the case of a small child, infant or neonate, over pressure ventilation could cause rupture of delicate lung tissue. Accordingly, in order to reduce this possibility, manual resuscitation apparatus typically includes a safety valve for venting air above a pre set pressure.
The prior art as also proposed equipping manual resuscitators with manometers or spirometers, and optionally CO2 and/or CO sensors or pressure transducers for measuring expiratory flow, expiratory tidal volume, expiratory minute volume and ventilator frequency. See, for example, U.S. Pat. Nos. 5,722,394; 7,051,596; 7,172,557 and 7,357,033. However, without an apparatus and method to provide correct alerting/notifications of proper rates/timing of ventilations, proper consistent administration can be difficult, especially in the field under traumatic situations.